Science Links Japan | Occurrence and crystal chemical features of protoferro-anthophyllite and protomangano-ferro-anthophyllite from Cheyenne Canyon and Cheyenne Mountain, U.S.A. and Hirukawa-mura, Suisho-yama, and Yokone-yama, Japan.

Occurrence and crystal chemical features of protoferro-anthophyllite and protomangano-ferro-anthophyllite from Cheyenne Canyon and Cheyenne Mountain, U.S.A. and Hirukawa-mura, Suisho-yama, and Yokone-yama, Japan.

Accession number;02A0930832

Title;Occurrence and crystal chemical features of protoferro-anthophyllite and protomangano-ferro-anthophyllite from Cheyenne Canyon and Cheyenne Mountain, U.S.A. and Hirukawa-mura, Suisho-yama, and Yokone-yama, Japan.

Author; SUENO S (Univ. Tsukuba, Ibaraki, Jpn) MATSUURA S (Taiheiyo Cement Corp., Chiba, Jpn) BUNNO M (Aist, Ibaraki, Jpn) KUROSAWA M (Univ. Tsukuba, Ibaraki, Jpn)

Journal Title;J Mineral Petrol Sci

Journal Code:G0150B

ISSN:1345-6296

VOL.97;NO.4;PAGE.127-136(2002)

Figure&Table&Reference;FIG.5, TBL.6, REF.31

Pub. Country;Japan

Language;English

Abstract;The crystal chemical features and occurrence of the new orthoamphiboles (space group Pnmn), protoferro-anthophyllite and protomangano-ferro-anthophyllite, are described. Protoferro-anthophyllites(PFA) are found in fayalite masses from granitic pegmatites at Cheyenne Canyon and Cheyenne Mountain, Colorado, U.S.A. and at Hirukawa-mura, Gifu Prefecture, Japan. Protomangano-ferro-anthophyllites(PMFA) are found in Mn-rich fayalite masses from granitic pegmatites at Suisho-yama, Fukushima Prefecture, and in bedded manganese ore deposits at Yokone-yama, Tochigi Prefecture, Japan. The empirical formulas of PFA from Hirukawa-mura and PMFA from Yokone-yama are (Fe1.54Mn0.42Mg0.14)Fe5(Si7.9Al0.1)O22(OH)2 and (Mn1.38Fe0.59)(Fe4.1Mg0.9Ca0.03)Si8O22(OH)2, respectively. The unit cell parameters of PFA are a=9.388(2), b=18.387(4), and c=5.347(1) .ANGS., and those of PMFA are a=9.425(2), b=18.303(4), and c=5.345(1) .ANGS.. These minerals are isostructural with synthetic protofluorian-lithian-anthophyllite (Pnmn, Z=2), and have a straight double-tetrahedral chain (O(5)-O(6)-O(5) angle of 177 and 179, respectively) and M(1), M(2), and M(3) octahedra of regular shape. PFA and PMFA are optically biaxial negative with refractive indices .ALPHA.=1.690, .BETA.=1.710, and .GAMMA.=1.726, and .ALPHA.=1.695, .BETA.=1.714, and .GAMMA.=1.731, respectively. The density (calc.) of PFA is 3.54 and that of PMFA is 3.44g/cm3. Some PFA and PMFA include fine clinoamphibole lamellae (space group C2/m). PFA may be produced by hydrothermal alteration of fayalite, and PMFA may be similarly produced by alteration of Mn-rich fayalite and also by metasomatism in bedded manganese ore deposits. (author abst.)

Related Articles;